Biomedical subjects
Publications and source records attributed to Philipp Peloschek.
A fast AAM search algorithm based on canonical correlation analysis (CCA-AAM) is introduced. It efficiently models the dependency between texture residuals and model parameters during search. Experiments show that CCA-AAMs, while requiring similar implementation effort, consistently outperform standard search with regard to convergence speed by a factor of four.
OBJECTIVE: The objective of our study was to assess the diagnostic value of CT enteroclysis compared with conventional enteroclysis in patients with Crohn's disease. SUBJECTS AND METHODS: Fifty consecutive patients (26 women, 24 men; mean age, 36.3 years; age range, 18-52 years) with histologically proven Crohn's disease underwent CT enteroclysis and conventional enteroclysis (median time interval, 21.7 days) during a symptomatic stage of their disease. Both techniques were compared with regard to diagnostic yield in assessing the presence and extent of disease. Imaging findings were compared with surgery, follow-up examinations, or both. RESULTS: CT enteroclysis and conventional enteroclysis were successfully performed in all 50 patients. Crohn's disease-associated radiographic changes were found in 44 patients (88%) using CT enteroclysis and in 42 patients (84%) using conventional enteroclysis. Significantly more Crohn's disease-associated abnormalities were diagnosed with CT enteroclysis than with enteroclysis (p < 0.01). Minimal inflammatory changes of the mucosa were diagnosed in 44 patients (88%) using CT enteroclysis and in 42 patients (84%) using enteroclysis. Both imaging methods depicted stenotic bowel segments in 34 patients (68%), and prestenotic dilatation was diagnosed in 20 patients (40%) with CT enteroclysis and in 15 (30%) with enteroclysis. Fistulas were found in 18 patients (36%) with CT enteroclysis and in eight (16%) with enteroclysis (p < 0.01). Skip lesions could be seen in 17 (34%) and three patients (6%), respectively (p < 0.01). Conglomeration of bowel loops tumors was diagnosed with CT enteroclysis in 13 patients (26%) and in three patients (6%) using conventional enteroclysis (p < 0.01). Only CT enteroclysis depicted abscesses in eight patients (16%) (p < 0.01). CONCLUSION: CT enteroclysis proved to be significantly superior to conventional enteroclysis in depicting Crohn's disease-associated intra- and extramural abnormalities. CT enteroclysis is the imaging method of choice and should replace enteroclysis in patients with Crohn's disease.
The approach to the differential diagnosis of rheumatic diseases using conventional radiography is systematic and module-oriented, which, with respect to future developments, forms the basis for computer-assisted diagnosis (CAD). The indications follow consensus-based referral criteria and attempts should be made to raise the evidence level of the recommendations. Investigation techniques have been improved in the last few years with the use of digital radiography. New imaging technologies may be available in the future that will achieve at least the same quality of images, while exposing patients to a significantly lower radiation dose. The interpretation of radiographical signs could be enhanced through a correlation with other imaging modalities. Computer-assisted techniques with image processing tools for automated measurements, lesion detection and in the form of expert systems are under development. With conventional radiography embedded in CAD systems, promising options will be available to enhance the differential diagnosis of rheumatic diseases.
PURPOSE: To compare image quality of digital chest radiographs using 2 modes of gradation adjustment. METHODS: We compared image quality and visualization of anatomic landmarks of 50 chest radiographs after digital processing using a semiautomatic mode with a fixed gamma of 2.6 and an automatic mode with individual gamma adaptation. RESULTS: The mean gamma was significantly higher (P < 0.001) with the automatic mode (3.0 vs. 2.6, respectively). Patient constitution had no impact on the automatically adapted gamma for PA but showed a significant correlation (P < 0.001) for lateral images. For PA, there was a preference (P < 0.016) of the semiautomatic mode in heavier patients whereas no difference was seen in slim patients. For the lateral projection, there was a general preference (P = 0.001) of the automatic mode. CONCLUSION: For PA radiographs, the semiautomatic mode provides superior results for heavier patients without compromising the quality in slim patients. For lateral radiographs, the automatic mode provides generally superior results.
OBJECTIVE: The aim of our study was to evaluate the diagnostic agreement of quantitative sonography of the radius and proximal phalanx and dual-energy X-ray absorptiometry (DXA) of the radius, lumbar spine, and femoral neck for the detection of osteoporosis. MATERIALS AND METHODS: In 95 women (mean age, 53 +/- 13 years) and 26 men (mean age, 53 +/- 13 years), DXA measurements of the lumbar spine (posterior-anterior, L1-L4) and the femoral neck, as well as quantitative sonography of the radius and proximal phalanx of the third finger were obtained. The percentage of patients below a given threshold was calculated for each imaging technique. A T score of less than -2.5 indicated presence of osteoporosis. Diagnostic agreement in identifying individuals with osteoporosis was assessed using kappa scores. RESULTS: Between 14% and 22% of the patients were classified as osteoporotic after DXA of the various regions of interest of the radius, 31% after DXA of the spine, 43% after DXA of the femoral neck, 32% after quantitative sonography of the distal radius, and 34% after quantitative sonography of the phalanx of the third finger. Correlation coefficients between T values for quantitative sonography and those for DXA varied between not significant and 0.54 at the different regions. Kappa analysis showed the diagnostic agreement among quantitative sonography and DXA to be fair to moderate (kappa = 0.38-0.48). The highest agreement was between quantitative sonography of the proximal phalanx of the third finger and DXA of the total radius (kappa 0.48; p < 0.05). CONCLUSION: Considerable diagnostic disagreement exists between quantitative sonography and DXA of the forearm, as is true for most quantitative techniques in the assessment of skeletal status. The lack of correlation makes quantitative sonography impractical for routine diagnostic use but might characterize different parameters related to bone quality.
In patients after chest trauma, imaging plays a key role for both, the primary diagnostic work-up, and the secondary assessment of potential treatment. Despite its well-known limitations, the anteroposterior chest radiograph remains the starting point of the imaging work-up. Adjunctive imaging with computed tomography, that recently is increasingly often performed on multidetector computed tomography units, adds essential information not readily available on the conventional radiograph. This allows better definition of trauma-associated thoracic injuries not only in acute traumatic aortic injury, but also in pulmonary, tracheobronchial, cardiac, diaphragmal, and thoracic skeletal injuries. This article reviews common radiographic findings in patients after chest trauma, shows typical imaging features resulting from thoracic injury, presents imaging algorithms, and recalls to the reader less common but clinically relevant entities encountered in patients after thoracic trauma.